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18 February 2019 | Story Leonie Bolleurs | Photo HO de Waal
Ground spiny Cactus pear
Shredded, sun-dried, and coarsely ground spiny cactus pear (Opuntia ficus-indica and O. engelmannii), ready to be included in balanced diets for ruminant livestock (cattle, sheep, goats) and wild antelopes.

Prof HO de Waal, researcher in the Department of Animal, Wildlife and Grassland Sciences at the University of the Free State (UFS), has developed a standard procedure for the processing of spiny cactus pear (Opuntia spp.) into livestock fodder. This will ultimately assist in the management of massive infestations of spiny cactus pear and help to convert underutilised farmland back to natural grazing land.

In addition to applying biological control agents, mechanical control is used to harvest alien spiny cactus pear, and the large volume of material is processed as livestock feed.

 

Introduced to South Africa

 

Three hundred years ago, seafarers visiting the Cape of Good Hope introduced the well-known invading alien spiny cactus pear to South Africa. These were later transported inland and by the 1950s about one million ha of South Africa had been invaded by the alien cacti.

Some regions in the Eastern Cape have been taken over by dense, impenetrable thickets of these cacti. Invasive alien plants (IAPs) such as cacti pose a direct threat to, among others, South Africa’s water security and productive use of land.

A range of methods is used to control IAPs, including mechanical, chemical, biological, and integrated control methods.

A control programme must include the three phases of initial control to drastically reduce the existing population; follow-up control of seedlings, root suckers, and coppice growth; and maintenance control on an annual basis to sustain low alien plant numbers.

 

Processing spiny cactus pears

 

According to Prof De Waal, the harvesting and processing of the spiny cactus pear is fairly simple. Although it requires a good measure of physical strength, perseverance, and the necessary protective clothing, the cacti can be processed by harvesting the plants; shredding the cladodes through a cladode cutter; then drying them in the sun, and lastly grinding it in a hammer mill. “The long spines are degraded mechanically by grinding the sun-dried cladode strips in a hammer mill before including it in balanced livestock diets,” said Prof De Waal.

Infestations will be opened, reclaimed, rehabilitated and the natural pastures (veld) allowed to revert back to grazing for livestock.

The National Resource Management Programme (NRM)P) will be approached for official support in clearing and rehabilitating massive areas of infestation by alien spiny cactus pear in the Eastern Cape. Such financial support will be an investment in reducing the infestation by invaders and the rehabilitation and sustainable use of natural resources in South Africa.

News Archive

Discovery in Scorpius constellation may signify clean energy for Earth
2017-01-23

 Description: Discovery in Scorpius constellation may signify clean energy for Earth Tags: Discovery in Scorpius constellation may signify clean energy for Earth

Earlier this year, a group of international astronomers
announced the discovery of an exotic binary star system,
AR Scorpii. The system is in the Scorpius constellation.
Photos: Supplied

See article on Nature’s website 

In future, stargazers and astronomers will look at the Scorpius constellation near the Milky Way with new eyes. Earlier this year, a group of international astronomers announced the discovery of an exotic binary star system, AR Scorpii. The system is in the Scorpius constellation.

Prof Pieter Meintjes, researcher in the Department of Physics at the University of the Free State (UFS), worked with four colleagues on what he describes as a “wonderful discovery”. This sensational discovery, which could lead to the production of cleaner energy on Earth, will be published in the research journal, Nature, early in 2017.

Model developed to interpret new set of measurements
The exotic binary star which was discovered consists of a red dwarf and a white dwarf revolving around each other every 3,5 hours. The binary system showed very prominent pulsations of 117 and 118 seconds respectively. The pulsations can be explained by a bundle radiation produced by the white dwarf star.

“These new observations have shown that the radiation is strongly polarised, a sign that we are dealing with synchrotron radiation here. Synchrotron radiation is produced by electrons accelerated to extremely high energy levels in the magnetic field of the white dwarf star,” says Prof Meintjes.

He developed a theoretical model to interpret a new set of measurements that was taken by the 1,9 m telescope and the 10 m SALT telescope at the South African Astronomical Observatory (SAA0).

Totally unique phenomenon could contribute to energy production on Earth
“I further indicated that the interaction between the magnetic fields of the white dwarf star and the red dwarf star induces secondary processes that specifically describe the behaviour of the radiation in the radio band and infrared band accurately. AR Sco is the first white-red dwarf binary system of which all the pulsated radiation could be explained by the synchrotron process, which is totally unique,” says Prof Meintjes.

According to Prof Meintjes, the value of the model lies in the fact that the processes which produce the radiation in AR Sco, can also be applied to produce energy on Earth.

 

Plasma reactors are based on roughly the same processes which apply in AR Sco, and with refining, it could be utilised to generate electricity in future. This will be much cleaner than nuclear energy.

 

The model developed by Prof Meintjes explains all the radiation in the system – from radio waves to X-rays – in terms of electrons accelerated to extremely high energy levels by electric fields in the system, which then produce synchrotron radiation over a very wide band of the electromagnetic spectrum.

Prof Meintjes is currently working on a follow-up article examining the evolution of the AR Sco, in other words, the origin of such a unique system and the final state towards which it is evolving. “My vision for the immediate future is therefore to develop a model for the evolution of the source concerned,” he says.

 

 

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